首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   3641731篇
  免费   304718篇
  国内免费   20577篇
耳鼻咽喉   48936篇
儿科学   114331篇
妇产科学   94807篇
基础医学   572272篇
口腔科学   95931篇
临床医学   331636篇
内科学   645992篇
皮肤病学   94622篇
神经病学   309148篇
特种医学   141296篇
外国民族医学   529篇
外科学   552045篇
综合类   125830篇
现状与发展   44篇
一般理论   2355篇
预防医学   305030篇
眼科学   83656篇
药学   253813篇
  137篇
中国医学   16795篇
肿瘤学   177821篇
  2022年   26850篇
  2021年   60072篇
  2020年   38799篇
  2019年   61272篇
  2018年   74930篇
  2017年   57920篇
  2016年   63314篇
  2015年   78908篇
  2014年   114348篇
  2013年   179597篇
  2012年   108517篇
  2011年   109698篇
  2010年   124592篇
  2009年   127650篇
  2008年   93598篇
  2007年   96954篇
  2006年   107036篇
  2005年   101722篇
  2004年   101200篇
  2003年   91216篇
  2002年   80067篇
  2001年   119996篇
  2000年   113345篇
  1999年   109194篇
  1998年   67536篇
  1997年   65071篇
  1996年   62758篇
  1995年   58161篇
  1994年   52114篇
  1993年   48416篇
  1992年   74756篇
  1991年   70388篇
  1990年   66066篇
  1989年   64772篇
  1988年   59723篇
  1987年   58385篇
  1986年   54868篇
  1985年   54605篇
  1984年   49594篇
  1983年   45168篇
  1982年   42217篇
  1981年   39595篇
  1980年   37264篇
  1979年   40312篇
  1978年   35632篇
  1977年   32326篇
  1976年   29655篇
  1975年   27968篇
  1974年   29070篇
  1973年   28076篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
991.
992.
993.
Abstract A high frequency of serum complement component C4A deficiency may explain the higher prevalence and greater severity of systemic lupus erythematosus reported in Australian Aborigines. Inherited deficiencies of serum complement components C4A, C4B, and C2 were examined in two Australian Aboriginal populations from Darwin and Alice Springs and compared with the prevalence of complement deficiencies in white Australian blood donors. The frequency of C4A deficiency alleles was 29% in Darwin Aborigines compared with 12% in Alice Springs and 17% in Canberra blood donors. Partial C4B deficiency was also higher in Darwin Aborigines than in the other populations. Inherited deficiency of serum complement component C2 was not observed.  相似文献   
994.
Authors with wide experience report that the Shouldice technique for repair of inguinal hernia is very effective. The technique has not gained widespread acceptance or notoriety. For example, the 13th edition of Textbook of Surgery, edited by Sabiston, devotes only one paragraph to this type of herniorrhaphy. Because of the excellent results reported by the Shouldice Clinic, this technique was adopted at the Augusta Veterans Administration Hospital, a teaching hospital of the Medical College of Georgia. Since 1976, a total of 604 Shouldice repairs have been performed by supervised house staff; 468 patients have been followed for up to 8 years and a recurrence rate of 1.3 per cent is reported. Although the follow-up is brief, the Shouldice hernia repair is widely applicable and good results are not dependent on wide experience alone.  相似文献   
995.
996.
997.
Summary A group of thirty children with nasal fractures was evaluated retrospectively by means of a questionnaire and hospital records. Age at the time of injury ranged from age 3 to 12 (mean = 8.6) years and mean follow-up period was 9 years. Eight patients reported some degree of nasal obstruction post reduction, but only one patient required submucous resection and two patients underwent septorhinoplasty for appearance. No patients reported class III malocclusion, or required orthodontic treatment or maxillofacial corrective surgery for maxillary hypoplasia. We concluded that a childhood nasal fracture treated by closed reduction does not have deleterious effects on facial or nasal growth.This work was supported in part by the Brigham Surgical Group Foundation, Inc., Boston, Massachusetts, USA  相似文献   
998.
Summary A new modification of microvenous anastomosis, which has increased patency rates while simultaneously decreasing the difficulty of the procedure, is presented in this paper. The primary purpose of this study was to compare the classical and the temporary stent techniques of microvenous anastomosis. Because of problems such as mixing and tangling of strings during insertion and tying of the last four sutures while applying the temporary stent technique, we decided to modify the procedure. The silastic tube was removed through an incision (venotomy), distant from the actual suture line. This modified technique and the other above mentioned techniques were carried out on rat femoral veins. The results indicate that this modification has increased patency rates, shortened the time of anastomosis and facilitated the procedure.  相似文献   
999.
W C Hsiao  P Braun  E R Becker  S R Thomas 《JAMA》1987,258(6):799-802
This article describes the design and methods of a study currently under way to develop a Resource-Based Relative Value Scale (RBRVS); an alternative basis for establishing the payment rate for the services and procedures (S/Ps) of physicians in medical and surgical specialties. Physician resource inputs to be measured include (1) S/P time, (2) pre-S/P and post-S/P times, (3) intensity, (4) practice costs, including malpractice premiums, and (5) the cost of specialty training. These five factors will be combined to produce an RBRVS denominated in nonmonetary units. In the initial phase of the study, data on time and intensity will be obtained through a national survey of physicians who perform these S/Ps. In the second, consensus phase of the project, the investigators will convene a panel of representatives of the medical profession, third-party payers, consumers, and other interested parties to examine areas of agreement and disagreement as to how an RBRVS should be used for policy purposes. The final results of this study are expected by the summer of 1988.  相似文献   
1000.
Using cortical cups in chloralose-urethanized rats, the in vivo release of cholecystokinin-like immunoreactivity (CCK-LI) from cerebral cortex was examined. Resting levels of cholecystokinin-like immunoreactivity ranged from 20 to 30 pg/20 min sample. The addition of potassium (40 mM) in excess, resulted in a highly significant elevation in the levels of CCK-LI in the cortical superfusate. Deletion of calcium and the substitution of cobalt (10 mM), resulted in a significant reduction in both resting release and the release otherwise evoked by the addition of potassium. Focal electrical stimulation of the cortex (20 Hz), resulted in a significant (1.9 +/- 0.2-fold, n = 8) increase in the levels of CCK-LI. The addition of glutamate (10(-6)-10(-4) M) of kainic acid (10(-8)-10(-6) M), also resulted in significant elevations in the levels of CCK-LI. The co-administration of a putative glutamate receptor antagonist, kynurenic acid (10(-4) M) resulted in a significant reduction in the levels of release otherwise evoked by the addition of glutamate, but not by electrical stimulation. The addition of GABA (10(-5)-10(-3) M) resulted in a dose-dependent decrease in the resting release of CCK-LI, and the release evoked by glutamate. Picrotoxin (10(-6)-10(-4) M), resulted in a highly significant increase in the levels of CCK-LI in the cortical effluent. These results are consistent with a tonic GABAergic inhibition of CCK-releasing neurons. The treatment of the animal with diazepam (30 mg/kg, i.p.) also resulted in a significant reduction in resting release and the release otherwise evoked by focal cortical stimulation.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号